A planar antenna device has hitherto been known, which includes a dielectric member having a recess in a bottom surface, a radiation electrode formed on the upper face of the dielectric member, a ground electrode formed on the bottom surface and in the recess of the dielectric member, electronic components disposed in the recess and connected to the radiation electrode and ground electrode, and a lid that covers the recess (see, for example, Patent Literature 1).
Such a planar antenna device can have built-in electronic components so that the entire thickness including the electronic components and planar antenna device can be reduced as compared to a configuration where the electronic components are disposed outside the planar antenna device. Such a planar antenna device can provide an electromagnetic shield for the electronic components by the ground electrode and the lid.